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Replace AsSliceU8 trait with zerocopy::AsBytes #692

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mkroening opened this issue Mar 26, 2023 · 7 comments
Closed

Replace AsSliceU8 trait with zerocopy::AsBytes #692

mkroening opened this issue Mar 26, 2023 · 7 comments
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@cagatay-y
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soundness Something is unsound.

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@mkroening
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Padding is uninitialized: Glossary - Unsafe Code Guidelines Reference

We do not check for padding, neither is AsSliceU8 unsafe.
zerocopy::AsBytes performs these checks.
@mkroening mkroening added the soundness Something is unsound. label Mar 26, 2023
@joannejchen
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Hi @mkroening! @scotran and I are part of a Virtualization course at UT Austin, and as part of a project we have to contribute to open source repositories. Can we take up this issue?

@mkroening
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Sure, do you want to do all three issues?

PS: To assign @scotran, he has to be a participant of this issue. Just write anything, then I can add him as well.

@joannejchen
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Yep, all three issues would be great!

@joannejchen
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joannejchen commented Apr 20, 2023 •
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Hi @mkroening! I was able to switch the VirtioNetHdr (currently reflected in the pull request created) from implementing AsSliceU8 to deriving AsBytes, but I ran into an issue when trying to change from AsSliceU8 to AsBytes for the Cmd and Rsp structs (https://github.com/hermitcore/libhermit-rs/blob/master/src/fs/fuse.rs#L293): #[derive(AsBytes)] is not supported on types with type parameters. Digging around, there seems to be a workaround (google/zerocopy#10), but this would require using repr(transparent), which then cannot be used alongside repr(C) or repr(packed), which would strip padding and possibly cause alignment issue.

I just wanted to touch base first as to whether this would be the desired approach, and if so, I can continue looking into how to derive AsBytes for structs with type parameters.

joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 20, 2023
Replace AsSliceU8 trait with zerocopy::AsBytes.
7f09f38 
Changed VirtioNetHdr to derive from AsBytes instead of AsSliceU8 and
changed related functions as necessary.

Fixes hermit-os#692.
joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 20, 2023
Replace AsSliceU8 trait with zerocopy::AsBytes.
f046402 
Changed VirtioNetHdr to derive from AsBytes instead of AsSliceU8 and
changed related functions as necessary.

Fixes hermit-os#692.
joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 20, 2023
Replace AsSliceU8 trait with zerocopy::AsBytes.
096b8d4 
Changed VirtioNetHdr to derive from AsBytes instead of AsSliceU8 and
changed related functions as necessary.

Fixes hermit-os#692.
@joannejchen joannejchen mentioned this issue Apr 20, 2023
Merged
joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 21, 2023
Replace AsSliceU8 trait with zerocopy::AsBytes.
5934f22 
Changed VirtioNetHdr to derive from AsBytes instead of AsSliceU8 and
changed related functions as necessary.

Fixes hermit-os#692.
joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 21, 2023
Directly implement AsBytes trait for Generic structs [experiemntal].
eb56619 
Attempts to completely remove the AsSliceU8 trait by directly
implementing AsBytes for generic structs because of lack of support for
generics using derive.

Fixes hermit-os#692.

Signed-off-by: Joanne Chen <joannejc@cs.utexas.edu>
joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 21, 2023
Directly implement AsBytes trait for Generic structs [experiemntal].
2b7bb6c 
Attempts to completely remove the AsSliceU8 trait by directly
implementing AsBytes for generic structs because of lack of support for
generics using derive.

Fixes hermit-os#692.

Signed-off-by: Joanne Chen <joannejc@cs.utexas.edu>
joannejchen pushed a commit to joannejchen/libhermit-rs that referenced this issue Apr 21, 2023
Replace AsSliceU8 trait with zerocopy::AsBytes for VirtioNetHdr struct.
697de57 
Changed VirtioNetHdr to derive from AsBytes instead of AsSliceU8 and
changed related functions as necessary. AsSliceU8 cannot be completely
removed yet because of lack of support for deriving AsBytes for
generics.

Fixes hermit-os#692.
@mkroening mkroening assigned cagatay-y and unassigned joannejchen Oct 31, 2023
@mkroening
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Just as an aside, there is a proposal for DynSized, with a very similar purpose to our AsSliceU8: rust-lang/rfcs#3536

@cagatay-y
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AsSliceU8 was removed with #1316. I think we can close this issue.

@mkroening
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Superseded by #1316

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